Environmental stresses are major limiting factors of plant development, growth and productivity. There are two general types of stress factors that can produce plant responses: (1) abiotic, which arise from excesses or deficiencies in the environment, and (2) biotic, which are imposed by other organisms.
Plant responses to stress factors trigger modulation of cellular metabolism, altered gene expression, changes in the growth rate, yield of phytomass, and reproductive capabilities. The following conditions, among others, cause plant stress: water-logging and submergence, drought, high or low temperatures, high or low soil salinity, inadequate minerals in the soil, too much or too little light, exposure to high concentrations of ozone and underexposure or overexposure to UV light.
Resistance or sensitivity of photosynthetic organisms to the stress depends on the species, genotype and development age. There are three major stress resistance mechanisms: (1) avoidance mechanisms which prevent exposure to the stress; (2) tolerance mechanisms which permit the plant to withstand stress; and (3) acclimation, i.e., alteration of plant physiology in response to stress.
Stress response is initiated when plants recognize stress at the cellular level and then stress recognition activates signal transduction pathways that transmit information within the individual cell and throughout the plant. Regulators of plant stress response include, but are not limited to, abscisic and jasmonic acids, osmotic adjustment factors, osmotin, protein stabilizing factors, heat shock proteins, specific mRNAs, Ca2+ ions and defense-related secondary metabolites.
The impressive ability of plants to sustain high levels of multiple stresses indicates that the defense mechanism is very complex in nature and involves multiple mechanisms of cellular adaptation and numerous metabolic pathways. Although this comprehensive and powerful defense system is not completely understood yet, utilization of its components and their interactions can be very beneficial.
U.S. Patent Application Publication No. 2009/0031446 discloses stress-related polypeptides and methods of use in plants: a transgenic plant transformed with an SLSRP coding nucleic acid, wherein expression of the nucleic acid sequence in the plant results in increased growth under water-limited conditions and/or increased tolerance to an environmental stress as compared to a wild type variety of the plant.
It was shown that synthesis of rutin, an antioxidative flavonoid in buckwheat herbs, is affected by different UV-B radiation levels: the rutin content is lower in plants growing at a level of UV-B light corresponding to 17% ozone depletion. Applied doses of UV-B radiation exert a state of stress, where limits of tolerance are exceeded and adaptive capacity is overtaxed, possibly resulting in a disturbance in rutin synthesis. The measurements suggest that ambient levels of UV-B radiation stimulate rutin accumulation in buckwheat plant compared with reduced UV-B level. The effect is more evident in leaves than in flowers. Enhanced UV-B radiation obstructs rutin accumulation (Samo Kreft et al., Journal of Experimental Botany, Vol. 53, No. 375, pp. 1801-1804, August 2002).
Broad physico-chemical diversity of stress-induced complexes and compounds and absence of universal specific “markers” suggest that capturing all stress-induced biologically active complexes and compounds in a single extract is not possible.
Therefore, there is a need for methods and systems for generating and isolating stress-induced bioactive fractions in photosynthetic plants. The present invention is directed to overcoming these and other deficiencies in the art.